Got Stuck with a G5 Now i want 2 revive

So I was all like after reading the poor reviews from other G5 users. Mac Forums should have an official "G5 Sell it for Parts" thread. Anyway, all I want to do is upgrade the OS, is that possible? I cannot upgrade Quicktime or Firefox though. And common websites like Youtube only open in a text only kind of format. Also, USB does not readily recognize media at times. Am I saddled with a hopeless lemon? Please give it to me straight if you must. Is it worth the adventure putting it together? The computer appears to work fine other than the disk drive ejects disks like toast on an episode of I Love Lucy! The meager specs are below....

The iMac G5 was my second iMac. It came with Panther pre-installed but it was successfully upgraded to both Tiger and Leopard as the years went on, and Leopard did appear to give the G5 a little boost in performance and, as such, a new lease of life.

I gave the G5 to a friend a long time ago now, but I was asked to update the OS for him as mentioned above.

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